Lasers, lamps and other sources of electromagnetic radiation are being increasingly utilized for the removal of unwanted hair, and for at least inhibiting, and in some instances preventing, the regrowth thereof, these techniques replacing techniques such as electrolysis and waxing previously utilized for hair epilation. Examples of such epilation techniques include U.S. Pat. Nos. 5,227,907 and 5,425,728 to Tankovich which involve applying a chromophore to the follicle and then applying radiation to the follicle of a wavelength selectively absorbed by the chromophore; U.S. Pat. No. 5,669,916 to R. Rox Anderson which involves epilation to remove the hair from the follicle, filling the empty follicle with a chromophore and then applying radiation to the follicle of a wavelength selectively absorbed by the chromophore to destroy the follicle; and U.S. Pat. No. 5,595,568 to R. Rox Anderson, et al. (the Anderson '568 patent) which involves applying energy of a wavelength preferentially absorbed by melanin in the follicle with sufficient energy and for a sufficient duration to destroy the follicle. However, while temporary hair removal can be achieved using the techniques indicated above at relatively low energy, for example 0.5 to 5 J/cm.sup.2, much higher energy pulses are required in order to achieve permanent, or near permanent, hair removal. For example, to achieve this objective, pulse energies in the 30-40 J/cm.sup.2 may be required.
However, such high energy levels present a number of potential problems. First, the spectial bandwidths normally utilized for most such hair removal techniques suggest the use of a ruby, alexandrite, diode or other laser. While such lasers are available which operate in the 30-40 J/cm.sup.2 range and above, such lasers are generally far more expensive than comparable lasers operating at lower energy. This results in systems designed to achieve permanent hair removal using these techniques being far more expensive than if these results could be achieved using lower energy lasers.
Second, while the high energy lasers or other radiation sources are effective for destroying a hair follicle, they reach the follicle through the epidermis which also contains significant quantities of melanin, particularly in its lower portion adjacent the dermal/epidermal (D/E) junction, which is also sometimes referred to as the basal layer. Such high energy laser pulses passing through the epidermis can thus result in significant damage to the epidermis. The Anderson '568 patent deals with this problem by cooling the epidermis prior to and during the application of laser pulses thereto; however, this cooling adds to the cost of the required equipment. The high energy pulses are also potentially dangerous for a person's eyes or other parts of the body and must therefore be handled with great care, normally by a physician or other highly trained individual. Lower energy pulses would therefore be safer to use, possibly eliminating the cost involved in cooling the epidermis, and potentially permitting hair removal procedures to be performed by less skilled, and therefore less expensive, personnel.
Another desirable characteristic in performing hair removal procedures is to be able to perform the procedure as quickly as possible. For example, it is preferable that the hair on a given area of a patient's body be removed in a matter of minutes, as opposed to an hour or more. While the patient appreciates not being subjected to the procedure over long periods, reducing the time for the procedure is particularly advantageous to the operator who can improve both his own productivity and that of what can be a relatively expensive piece of equipment thereby enhancing the profitability of his business. However, as is discussed in greater detail later, the time required to cover a given area is inversely proportional to the fluence and directly proportional to power. Therefore, prior art systems requiring high fluence for permanent hair removal have either operated relatively slowly, thereby requiring long periods of time for removal of hair from large areas such as the legs, and/or have required a very high power, and thus very expensive, source. Therefore, for a given power source, reducing the required fluence from for example 30 J/cm.sup.2 to 5 J/cm.sup.2 could result in a six-fold reduction in the time required for a given procedure.
For the reasons indicated above, and others, a need exists for an improved technique for hair removal which provides long-term inhibition of hair regrowth and potentially permanent hair removal at fluences far below the 30-40 J/cm.sup.2 of current techniques, and preferably at fluences in the 1-5 J/cm.sup.2 range.